Similar presentations

2 Technically, what is a pavement?“Black Top” or “Tarvy” ?“to pave” means “to cover with asphalt, gravel, concrete, macadam, etc.”1 Unfortunately, most people equate the term “pavement” with terms like “Black Top” or “Tarvy”2 This is because of the verb “pave” which means “to cover with asphalt, gravel, concrete, macadam, etc.3 What is actually implied by this is that a pavement is a surface of specially engineered material placed on any existing surface…but why?A surface ?

3 Why build pavements? Transportation Originally, footpaths sufficedIncreasing traffic and loadsQuality Issues: drainage, subgrade materialsTransportation seems to be the historical impetus to building roads.Originally, the transportation of people and light loads required only footpaths and no particular engineering until a major waterway needed to be crossed that could not be safely forded.As the demands of commerce increased traffic and loads, the issues of drainage and subgrade material properties were soon recognized as problems that required engineering solutions. Enter John McAdam a Scottish engineer who lived from 1756 to 1836.John Macadam,

4 5.01 Define the term pavement as it is given by the MTO's Pavement Design and Rehabilitation Manual ."Pavements are layered structures of selected and processed materials which have been designed to resist surficial wear, to support wheel loads and provide drainage of water."

5 PAVEMENT TYPES5.02 Identify the various pavement types according to the following three classification methods:a) Surface Typeb) Load Transmissionc) Composition1. Among the many ways of classifying pavement types, these are the 3 most common:a) by surface typeb) by load transmissionc) by composition/constructionThere are two basic categories of pavement based on surface type: paved or unpaveda) Surface Type: Bound or Unbound

15 5.06 Describe the materials and manufacture of Hot Mix Asphaltic Concrete.a mixture of fine and coarse aggregate with asphalt cementManufacture:components are heated and mixed in a central plantmixture is hauled to site in special trucks and placed on the road using an asphalt spreader

17 5.08 Describe the materials and manufacture of Cold Mix Asphaltic Concrete.a mixture of emulsified asphalt or liquid (cutback) asphalt and aggregateManufacture:components are mixed at ambient air temperaturecan be mixed in a central plant or in-situ on the road surface with a travelling mixer such as the Midland Mix Paver or road mix mulch pavements

18 Manufacture (Continued):aggregate and emulsified asphalt are delivered to Midland Mix Paver separately and blended in a pug millaugers distribute mixture to a screed which uniformly controls the thickness of the cold mix layeronce the emulsified asphalt in the mixture surface starts to break or set, the mixture is compacteduse in Ontario generally restricted to low volume rural roads, where HMAC surfaced pavements are not required

19 5.09 Describe the materials used and general placement method for Surface Treatments.consist of an application of emulsified or liquid asphalt and select aggregate over a prepared granular base or existing surface

22 5.12 Identify the origin of asphalt cement and the MTO grade specifications (test and designations).the majority of asphalt cements come from petroleum distillation as do liquid (cutback) asphalts and asphalt emulsions (see next slide)MTO has graded asphalt cements by standard penetration number (PEN); eg: 85/100 (hardest), 150/200, 300/400, (softest)SUPERPAVE is a new mix design method that replaces this grading system

24 5.13 Describe the 2 conflicting problems related to asphalt cement grade faced in Ontario.if a soft grade is used then rutting is a problem in the hot summersBefore:After:if a hard grade is used then low temperature (transverse) cracking is a problem in the winter